A much easier method for diversions but you do need to know where you are!
Put one end of the pencil on where you are (think of it as the centre of a clock) the other where you want to go to.
what is it o'clock ie 7 x 3 = 21 then add a 0 on the end = 210 degrees
what is it o'clock ie 2 x 3 = 6 then add a 0 on the end = 60 degrees
If between numbers eg 9 and 10 then 270/300 half way = 285 degrees.